Roller contactor for moisture meters or the like



Oct. 31, 1950 R. s. HART 2,527,315

- ROLLER CONTACTOR FOR MOISTURE METERS OR THE LIKE F iled Oct. 4, 1946 13 INDICATOR INVENTOR.

RAYMOND SHAW Patented Oct. 31, 1950 OFFICE ROLLER CONTACTOR FOR MOISTURE METERS OR THE LIKE Raymond S. Hart, Brooklyn, N. Application October 4, 1946, Serial No. 701,251

1 Claim.

The present invention relates to improvements in contactors for moisture meters or the like and, more particularly, to roller contactors adapted foruse with a running web of sheet material.

Such a roller contactor may be used to apply an electric current to a sample portion-of the material which is to be examined, for instance, for its moisture content by determining its electrical conductivity, a method of making such measurements having been disclosed in my earlier U. S. Patent No. 2,183,333 dated December 12, 1939.

Readings may be obtained by connecting one or more rollers of the contactor to a sensitive device, such as the meter described in my aforesaid patent. When such readings are attempted between a single roller and ground, or between a pair of rollers connected to the input of the measuringdevice, severe static conditions primarily due to friction frequently interfere with the making of accurate measurements; this is especially true with materials which are running at great speed and which are relatively dry. It has been observed, however, that the static introduced by a pair of rollers reads in reverse polarity if the rollers are interchanged so that the trailing roller is placed in leading position,

rollers l3 and [4 on axles I! and I8, respectively, these axles being secured by nuts Hi to a frame 20 of insulating material. The frame 20 is preferably made of a moldable plastic material, such as an acrylate and methacrylate resin, and has a metal handle 2| fastened to it by means of bolts 22 and nuts 23.

Electrically, the four rollers are cross-connected to form two pairs of diagonally positioned electrodes one of which may be grounded, as has been shown in Fig. 3. The two pairs ll, [4 and I2, I 3 are connected to respective conductors leading to the input circuit of the indicator, not

and vice versa, with respect to the oncoming materialv The principal object of my invention is to provide a roller contactor having electrodes arranged in such a manner as to eliminate any objectionable interference by static charges with the measurements to be taken.

With this and other, objects in view, which will be apparent in the course of the following description, I provide in accordance with the present invention a contactor having a plurality of rollers, including at least two roller-electrodes arranged for the mutual neutralization of their static charges with respect to some further electrode or electrodes.

The invention will be described with reference to two specific embodiments shown in the accompanying drawing in which Fig. l is an elevation, partly in section, and

shown. It will be seen immediately that each pair of electrodes comprises one roller in leading position and one in trailing position with respect to an aligned roller of the other pair, thus being arranged to have the effects of their respective charges cancel each other. The rollers make contact with the material to be tested with their outer cylindrical working surfaces which in technical language is commonly referred to as their faces.

In Fig. 3, the grounded upper conductor is connected to a fixed-potential electrode and the lower conductor to the control electrode of the indicator. Since the distance between rollers II and I4 on one hand and between rollers I2 and I3 on the other hand are equal, the latter two rollers will have similar potential with respect to ground and the same current will flow in the two circuits which include, respectively, the pairs of correlated electrodes ll, l3 and I 2, M. The current measured by the indicator will be the sum of the two branch currents, or double the current through either circuit; thus the resistance between a pair ofcorrelated electrodes may be readily determined. On the other hand, in keeping with the principles outlined above, the parasitic currents due to static charges will substantially compensate each other, leaving the indicator virtually unalfected.

Additional modifications and adaptations of the contactor according to this invention will unjdoubtedly occur'to those skilled in the art, it

being understood that departures from the preeise embodiment described and illustrated may be made without exceeding the spirit and scope of my invention as defined in the appended claim.

I claim: V

A roller contactor comprising an insulating frame having a rectangular opening; a handle bridging said opening; two pairs of pivots mounted in said frame with their free ends extending into said rectangular opening; two pairs of rollers rotatably mounted on said pivots inside said rectangular opening such that all the working faces of said four rollers are parallel to a common plane, and electrical conducting means connecting said rollers in two groups whereby two rollers 01: one polarity are separated by two rollers of the opposite polarity. N RAYMOND S. HART.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 4 UNITED STATES PATENTS Name Date Dewald Sept. 23, 1919 Gibbs June 8, 1926 Fortier Nov. 29, 1927 Andersen Sept. 1, 1931 Siegenheim Feb. 6, 1940 Sparrow Nov. 18, 1941 FOREIGN PATENTS Country Date Norway June 2, 1925 France Dec. 6, 1933 

